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FAN5234

Fairchild Semiconductor
Part Number FAN5234
Manufacturer Fairchild Semiconductor
Description Mobile-Friendly PWM/PFM Controller
Published Mar 30, 2005
Detailed Description www.fairchildsemi.com FAN5234 Mobile-Friendly PWM/PFM Controller Features • Wide input voltage range (2 to 24V) for Mo...
Datasheet PDF File FAN5234 PDF File

FAN5234
FAN5234

Overview
www.
fairchildsemi.
com FAN5234 Mobile-Friendly PWM/PFM Controller Features • Wide input voltage range (2 to 24V) for Mobile systems • Excellent dynamic response with Voltage Feed-Forward and Average Current Mode control • Lossless current sensing on low-side MOSFET or precision over-current using sense resistor • VCC Under-voltage Lockout • Power-Good Signal • Light load Hysteretic mode maximizes efficiency • QSOP16, TSSOP16 • 300Khz or 600Khz operation General Description The FAN5234 PWM controller provides high efficiency and regulation with an adjustable output from 0.
9V to 5.
5V that are required to power I/O, chip-sets, memory banks or peripherals in high-performance notebook computers, PDAs and Internet appliances.
Synchronous rectification and hysteretic operation at light loads contribute to a high efficiency over a wide range of loads.
The hysteretic mode of operation can be disabled if PWM mode is desired for all load levels.
Efficiency is even further enhanced by using MOSFET’s RDS(ON) as a current sense component.
Feed-forward ramp modulation, average current mode control, and internal feedback compensation provide fast response to load transients.
The FAN5234 monitors these outputs and generates a PGOOD (power good) signal when the soft-start is completed and the output is within ±10% of its set point.
A built-in over-voltage protection prevents the output voltage from going above 120% of the set point.
Normal operation is automatically restored when the overvoltage conditions go away.
Under-voltage protection latches the chip off when the output drops below 75% of its set value after the soft-start sequence is completed.
An adjustable over-current function monitors the output current by sensing the voltage drop across the lower MOSFET.
Applications • Mobile PC regulator • Hand-Held PC power Typical Application VIN (BATTERY) = 2 to 24V 1 VCC VIN BOOT C1 D1 +5 C5 L1 Q1B 10 9 12 LDRV PGND ISNS VSEN VOUT 15 C2 +5 C4 11 FAN5234 R5 14 ILIM EN SS1 4 3 7 16...


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